Taihu Basin Research Articles

ABSTRACT This study investigates the spatiotemporal evolution of hydrological connectivity in China's highly urbanised Taihu Lake Basin from 1985 to 2020, integrating remote sensing, graph theory, and landscape metrics to assess structural and functional connectivity dynamics. Results reveal a 7.85% decline in total water area and a 44.9% reduction in river‐network density (2005–2020), with structural connectivity initially improving ( α : +81%, 1985–2005) before declining by 6%–17% (2015–2020). Functional connectivity exhibited strong spatial heterogeneity, with high‐connectivity zones concentrated in the eastern basin (IC > −3.0) and degraded areas in urban centres (IC < −5.0). Basin‐wide mean IC correlated positively with mean annual rainfall ( r = 0.59), especially in the HX region ( r = 0.88). The construction of hydraulic works in the Taihu Basin has focused chiefly on channel rectification, inter‐basin diversion, and polder management, with various quantities in different regions. Therefore, human impacts varied spatially: inhibiting connectivity (CC < 0, Trend CC < 0) in the southeast but generally promoting it elsewhere (north, Trend CC > 0), revealing regional disparities in anthropogenic effects. The study advances prior research by providing the first 35‐year integrated assessment and offers a policy‐relevant template for balancing hydrological integrity with urbanisation pressures in densely populated river–lake systems.

ABSTRACTOwing to the substantial spatiotemporal variability and intricacy in the hydrodynamic and water quality responses to water diversion, the determination of impact on the aquatic environment has been predominantly qualitative. The quantitative assessment of the impact of anthropogenic activities (water diversion) on the aquatic environment has the potential to enhance the accuracy of a comprehensive benefit evaluation. The present study utilised hydrological data, encompassing flow rate (Q) and water quality index (WQI) in the lakes Taohu and Gehu basin (TGHs), from two typical water resource allocations in the Taihu basin. The study revealed how hydrodynamics and water quality in response to water diversion. Furthermore, it introduced the concept of “water diversion impact value” to quantify the impacts of water diversion on the aquatic environment. The results indicated when the overall water diversion effect showed enhancement in water quality, the WQI impact value was positive alongside a negative Q impact value (); Conversely, when water diversion improved hydrodynamic conditions, the WQI impact value was negative accompanied by a larger positive Q impact value (). Principal component analysis (PCA) further validated these results, demonstrating that prolonged and stable diversion was positively correlated with WQI, while short and fluctuating diversion was positively correlated with Q, thereby supporting the method of evaluating the effects of water diversion using impact values. In addition, the TGHs was divided into three distinct components: namely mainstream areas, tributary areas, and lake areas, in accordance with the respective hydrological compartment. The present study set out to explore the response mechanisms of three distinct hydrological compartments to water diversion. The findings revealed that the impact extremes predominantly occurred in the mainstream areas, exhibited minimal occurrence in lake areas, and manifested within the range between the two in tributary areas. The diversion impact value has been shown to be a reliable metric for evaluating the effects of water diversion, thereby providing substantial theoretical underpinnings for the enhancement of aquatic environments.

Contrasting community stability and functional dynamics of denitrifying anaerobic methane-oxidizers in rivers.

Altering water flow pathway to enhance nutrient retention in lowland areas.

Spatial distribution and ecological risks of neonicotinoids in surface waters of Eastern China.

Cities, as a geographical unit with the greatest intensity of human socio-economic activities, have become the core nodes that disrupt the natural cycle of phosphorous (P) and regulate P flow toward sustainable development. However, P flows and its balance in many Chinese cities are largely unknown. This study employed the substance flow analysis (SFA) method to construct a P flow model for the food chain in Changzhou, a representative lakeside city in the Taihu Basin. From 2000 to 2021, the total P input and stock in Changzhou city's food chain system declined from 5,698.55 tP and 5,219.55 tP to 2,391.26 tP and 1,760.46 tP, respectively. Conversely, the total P loss surged from 478.99 tP to 630.79 tP, suggesting an open and unrestricted P flow. The P use efficiency (PUE) in animal production increased from 30.11% in 2000 to 37.65% in 2021, while that in crop production and the overall food chain increased from 51.41 and 65.74% in 2000 to 71.94% and 80.16% in 2021. Scenario analysis revealed that reducing food P uptake could lower total food chain P inputs and dependence on external P. Fertilizer recommendations could boost the PUE of crop production from 71.94% to 81.34%. Besides, urine diversion and waste incineration scenarios significantly decreased P accumulation in the food chain. Improving sewage treatment technology could further cut P discharge. An adaptive food chain P flow management framework was proposed. Leveraging the self-management and replicability of cities, this framework can be easily implemented in other regions and has the potential to be scaled up nationally, aiming to mitigate P loss and enhance P utilization efficiency.

ABSTRACTThis study proposes a distributed unit hydrograph (DUH) method to address the challenge of simulating overland flow concentration in plain river network regions. The DUH framework defines generalized river network polygons (RNPs) to represent flow convergence zones and estimates runoff travel times based on a calibrated confluence velocity parameter, circumventing the need for high‐resolution topographic data. The method was applied to the Taihu Basin, where 16 subregions were analyzed under different spatial scales and overland flow velocities. Results show that the DUH method significantly enhances model performance compared to the traditionally used proposed unit hydrograph (PUH) approach. Specifically, DUH reduced the root mean square error (RMSE) of simulated water levels by up to 40%, improved the coefficient of determination (R2) by 0.1–0.2, and reduced the average flood peak lag from 2.1 days to 0.7 days. The model exhibited optimal accuracy at a grid scale of 200 × 200 m, achieving a balance between smooth hydrograph formation and computational efficiency. These findings underscore the DUH method's applicability for flood simulation and decision‐making in low‐relief, hydraulically complex regions with limited microtopographic data availability.

Priority emerging contaminants in the Taihu Basin (China): occurrence, risk assessment, and control strategies

Transboundary water governance faces persistent challenges due to mismatches between natural hydrological boundaries and political administrative boundaries. This study examines the evolution and mechanisms of intergovernmental cooperation in the Taihu Basin (1987–2024), addressing how cooperation forms, evolves, and sustains amid conflicting priorities. Using a mixed-methods approach, we analyzed 106 policy documents, government reports, and stakeholder interviews to map governance stages, cooperation networks, and policy themes. Results reveal three phases in transboundary water governance in Taihu Basin: (1) a centralized hierarchy (1987–2007) dominated by vertical mandates; (2) a hybrid stage (2008–2018) with rising horizontal cooperation driven by crisis responses like the 2007 cyanobacteria outbreak; and (3) a networked stage (2019–2024) integrating diagonal mechanisms that bridged hierarchical gaps and scaled grassroots innovations. Key findings show diagonal relations reduced bureaucratic delays, enabling bottom-up practices like joint river chief systems to become regional policies. While grounded in the Taihu Basin context, this study provides a compelling case of institutional coupling that may inform governance in other transboundary basins, where vertical authority, horizontal reciprocity, and diagonal experimentation coexist dynamically. This study offers a model for balancing administrative fragmentation and ecological integrity, emphasizing adaptive networks over rigid hierarchies. These insights provide a feasible solution approach for addressing transboundary water resource governance challenges in similar institutional environments.

This paper introduces the sources of agricultural runoff pollution and reviews control technologies for agricultural runoff pollution from the perspective of "source control-process interception." It analyzes integrated technology cases in real-world scenarios, using the Taihu Basin in Jiangsu Province and Jiaxing City in Zhejiang Province as examples to illustrate the application effects of the "source control + process interception" and "smart monitoring + dynamic regulation" systems. These integrated technology models have significantly reduced pollutant levels in agricultural runoff and improved water quality in surrounding waters, providing an effective solution for controlling non-point source pollution from agriculture. Current ecological measures still face challenges such as insufficient long-term effectiveness and technical-economic conflicts. To address these issues, it is recommended to innovate modular technologies, implement policy mechanisms, establish an integrated mechanism for infrastructure construction, management, and utilization through diversified funding mechanisms, and build intelligent platforms to enhance system efficiency. Ultimately, a three-step strategy of "pilot breakthrough-regional promotion-national networking" will achieve large-scale, intelligent, and sustainable governance of agricultural non-point source pollution.

Early warning and management of excessive discharge of water pollutants in municipal wastewater treatment plants based on fluctuation coefficients.

Abstract Clarifying carbon (C) cycling in small ponds is vital for understanding C transport in lowland agricultural landscape. Quantifying C flux is crucial for learning C cycling, but is challenging due to its complex cycling and significant impacts from intensive human activities. Here, we developed a process‐based model (CDP) to achieve a daily estimation of C dynamics in agricultural ponds within lowland artificial watersheds (polders), and proposed a dual evaluation approach (concentration and flux) to assess the model's performance using two data sets obtained from eight typical polders in the Lake Taihu Basin. The developed model captured pond C dynamics, achieving a Nash‐Sutcliffe efficiency of 0.44 ± 0.27. Our C flux estimations based on the newly‐developed model showed large C emissions, primarily through carbon dioxide (CO2) (497.5 g C m−2 yr−1), along with significant C burial (27.8 g C m−2 yr−1) with a hot moment in summer. Scenario simulations revealed the distinct impacts of pond C emissions and burial associated with the growth and death of phytoplankton and macrophytes. A 10% increase in macrophyte growth rates associated with a 1.8 g C m−2 yr−1 increase in CO2 emission, while a similar increase in phytoplankton growth rates related to a 12.2–16.2% increase in C burial. This study revealed a quick response of C flux to phytoplankton‐macrophyte dominance, and highlighted the high potential of the process‐based model for high‐resolution (daily) quantification of C fluxes, thereby enhancing our understanding of C cycling in lowland agricultural ponds.

ABSTRACTDue to the intensive human activities, lots of hydraulic facilities were constructed and have a significant impact on hydrological processes and spatial migration of urban floods. For coastal plain regions, the suffering from rainstorms and storm surges, which was always neglected in previous studies, makes the impact more complex. Thus, the potential impact was observed based on a hydrodynamic model with real‐time operations of hydraulic systems. To improve the confidence of the simulation, a joint copula model between maximum rainfall and contemporaneous maximum tide water level was built, which makes up for the lack of consideration in previous coastal flood simulations. Results of quantitative simulation showed that the projects of the Large Encirclement Project in Suzhou urban (LEP) prevented the flood in urban areas efficiently but transferred the flood to the suburb. The Diversion‐Drainage System along the Yangtze River (DDS) had a larger impact on the hydrological processes in the northern regions. This will be of great benefit to the flood management in the Taihu Basin.

Response of extreme precipitation to urbanization in Taihu Basin considering regional heterogeneity

Long-term remote sensing monitoring of the spatiotemporal evolution of aquatic vegetation and algal blooms in shallow lakes: A case study of Lake Changdang in the Taihu Basin (1985-2021)

Nitrogen removal efficiency and driving factors in typical ponds from a hilly region in the upper Lake Taihu Basin

Characteristics of nitrogen dynamics and impact of nitrate enrichment in the agri-food system of the Taihu Basin

Enhancing flood resilience has become crucial for watershed flood prevention. However, current methods for quantifying resilience often exhibit coarse spatiotemporal granularity, leading to insufficient precision in watershed resilience assessments and hindering the accurate implementation of resilience enhancement measures. This study proposes a watershed flood resilience assessment method based on a system performance curve that considers thresholds of inundation depth and duration. A nested one- and two-dimensional coupled hydrodynamic model, spanning two spatial scales, was utilized to simulate flood processes in plain river network areas with detailed and complex hydraulic connections. The proposed framework was applied to the Hangjiahu area (Taihu Basin, China). The results indicated that the overall trend of resilience curves across different underlying surfaces initially decreased and then increase, with a significant decline observed within 20–50 h. The resilience of paddy fields and forests was the highest, while that of drylands and grasslands was the lowest, but the former had less recovery ability than the latter. The resilience of urban systems sharply declined within the first 40 h and showed no signs of recovery, with the curve remaining at a low level. In some regions, the flood tolerance depth and duration for all land use types exceeded the upper threshold. The resilience of the western part of the Hangjiahu area was higher than that of other regions, whereas the resilience of the southern region was lower compared to the northern region. The terrain and tolerance thresholds of inundation depth were the main factors affecting watershed flood resilience. The findings of this study provide a basis for a deeper understanding of the spatiotemporal evolution patterns of flood resilience and for precisely guiding the implementation and management of flood resilience enhancement projects in the watershed.

This study investigates the spatial correlation and service flow of supply and demand for water purification ecosystem services at multiple scales (i.e., the Taihu Lake Basin, sub-basin, and county) by quantitatively assessing the supply–demand relationship of nitrogen and phosphorus and introducing the SPANS algorithm to characterize the service flow paths. Through quantitative analysis, the supply–demand relationship between nitrogen and phosphorus was evaluated, and the SPANS algorithm was introduced to characterize the service flow paths. The results show that the water purification ecosystem services in the southwestern region and around Taihu Lake exhibit a good supply–demand balance, while a significant supply–demand deficit is observed in the northern and southeastern regions. Service flow analysis indicates that surplus areas are primarily concentrated in hilly and urbanized central regions, whereas deficit areas are mainly located in non-urban centers. Based on these findings, ecological compensation suggestions are proposed, including dynamic adjustment, differentiated compensation, cross-city collaboration, and guidance of social capital participation, to promote continuous improvement in water quality and sustainable development within the basin.

Detection of flood trends and drivers in the Taihu Basin, China